package BiShi.first;

public class bina_search {

    //寻找左边界
    int left_bound(int[] nums, int target) {
        if (nums.length == 0) return -1;
        int left = 0;
        int right = nums.length; // 注意

        while (left < right) { // 注意
            int mid = (left + right) / 2;
            if (nums[mid] == target) {
                right = mid;
            } else if (nums[mid] < target) {
                left = mid + 1;
            } else if (nums[mid] > target) {
                right = mid; // 注意
            }
        }
        return left;
    }

    //寻找右边界
    int right_bound(int[] nums, int target) {
        if (nums.length == 0) return -1;
        int left = 0, right = nums.length;

        while (left < right) {
            int mid = (left + right) / 2;
            if (nums[mid] == target) {
                left = mid + 1; // 注意
            } else if (nums[mid] < target) {
                left = mid + 1;
            } else if (nums[mid] > target) {
                right = mid;
            }
        }
        return left - 1; // 注意
    }
}


